Many industries, including oil and mining, certain manufacturing, waste treatment and disposal, as well as emergency services, rely on various gas detection systems to protect their workforce and infrastructure from exposure to toxic, corrosive, combustible, or flammable volatiles in the field. Exposure to even trace (few parts per million or less) amounts of airborne substances such as ammonia (NH3), arsine (AsH3), carbon monoxide (CO), chlorine (Cl2), hydrogen cyanide (HCN), hydrogen sulfide (H2S), phosphine (PH3), and sulfur dioxide (SO2) can be very harmful to human health and, in some instances, can corrode valuable equipment. Therefore, a practical gas detector must possess exquisite sensitivity and selectivity for the relevant detrimental substances.
Currently, there exist multiple approaches to gas detection. The working mechanisms of conventional sensors, which can be packaged into portable or fixed devices, rely on semiconducting elements, oxidative/catalytic chemistries, or optical/spectroscopic measurements. While most of these detectors demonstrate very high analyte sensitivities in controlled environments, operation in complex multi-component ambient air mixtures, that include overwhelming amounts of non-essential yet spectroscopically active species, often challenges even the most sophisticated systems. In addition, some sensing schemes are affected by high water vapor content in the air (humidity) and variations in atmospheric pressure, while others have dangerously slow response times. Consequently, a highly sensitive, specific, fast, and reliable gas detection system, which functions under ambient conditions, is highly sought after for safeguarding workers within the affected industries, and for environmentally threatened populations.